• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.432-437
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• 1996

The observed characteristics of magnetic oscillations in L-H transition and disruption are described. Two kinds of MHD magnetic probes are used in order to cover broadband frequency range from 1.3 kHz to 300 kHz in the H-mode. Depending on the probe's position and frequency, different characteristics are observed. Precursor like oscillation in L-H transition, and the difference between sawtooth and ELM are discussed. All disruptions during the current rising phase are related with m＝2 or m＝3 mode. Different disruption characteristics for different operation conditions could be found in the MHD probes.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.351.1-355
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• 1998

Network-based real-time multimedia applications require guaranteed performances of communication service. Also according to increased bandwidth and processing performance in the future high speed networks, it is possible to make multimedia real-time applications such as distributed real-time applications including video conference, medical imaging, and video education. These applications have characteristics of stringent performance requirements in terms of delay, delay jitter and maximum loss rate. This paper proposes a new delay control for Broadband networks with FCFS queueing. The delay control provides an alternative solution to a current problem in real-time communication; traffic distortion, which makes it difficult to meet such real-time requirements. In simulations, it shows that the proposed delay control can guarantee local and end-to-end delay.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1599-1605
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• 2011

From now on, power line communication was made use of controling using 450 kHz narrow band, but as the PLC technology developing, in the near future get to the commercial step that is broadband PLC upto 30 MHz. In this paper, analyze the possibility of moving picture transmission for adapting surveillance camera which is among of the application of PLC. To analyze characteristics of channel, estimate the noise and impedance of lab, office, home. In case of noise, there is no problem to communicate each other because of 20 ~ 50 dB gain. In case of impedance, average impedance is about 100 ohm, it satisfy standards of designing modem but because max and min values get out of expectation there are some problem to acquire fully capacity of modems. Its condition is the same as transmission of multimedia data. In this test as more packets, as more handling rate, in lab, for the case that transmit 1,518 byte as the speed of 6 Mbps handling rate is upto 100%, it means possibility of moving picture transmission as the 6 Mbps speed. For delayed time there is no relationship about transmitted packets. As a result, there is no problem about applying surveillance camera via the PLC. And more cameras can work within PLC for considering the number of transmitted frames.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.6 s.99
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• pp.687-696
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• 2005

Acoustic power spectrum of the upstream and downstream sound field due to an isotropic frozen turbulent gust impinging on a cascade of flat plate airfoils are computed by using a analytic formulation derived from Smith's method, and Whitehead's LINSUB codes. A parametric study of the effects on sound power of the number of blades and turbulence length scale is performed with an emphasis on analyzing the characteristics of sound power spectrum. Through the comparison of the computed results of sound power, it is found that acoustic power spectrum from the 2-D cascade subject to a ingested turbulence can be categorized into two distinct regions. one is lower frequency region where some spectral components of turbulence do not contribute to the cut-on acoustic modes and therefore the effect of the cascade geometry is more dominant ; the other is higher frequency region where all of spectral components of turbulence make contributions to cut-on acoustic modes and thus acoustic power is approximately proportional to the blade number.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.57-58
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• 2018

In this paper, we studied a design method for a quasi-Yagi antenna operating over a broad bandwidth covering the UHF RFID(902-928 MHz) and GNSS(1,164-1.605 MHz). The proposed antenna is composed of three elements(dipole, reflector, and director) and fed by a coplanar waveguide. To reduce its size, a balun is integrated inside the antenna, and the ends of both the dipole and reflector are bent. Broadband impedance matching was obtained by placing the director near to the dipole and loading a chip capacitor inside the antenna. The antenna, designed through simulations, was fabricated on an FR4 substrate with 0.8 mm thickness. The experiment results for the antenna characteristics agree very well with the simulation.

• Journal of electromagnetic engineering and science
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• v.2 no.1
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• pp.16-21
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• 2002

On the contrary to the progress of the electronic industry and radio communication technologies, many social problems such as EMI, due to unnecessary electromagnetic(EM) wave are serious with the increased use of EM wave. It is required that the absorbing capability of an EM wave absorber is more than 20 dB, the bandwidth of which is required from 30 MHz to 18 GHz to satisfy the international standard about an anechoic chamber for EMI/EMS measurement$^{[1]}$TEX>. However, the absorbing frequency band of the conventional EM wave absorbers satisfying more than 20 dB is very narrow, for examples, from 30 MHz to 400 MHz in ferrite tile type and from 30 MHz to 870 MHz in ferrite grid type, respectively. In this paper, we proposed and designed a new tripe absorber with broadband characteristics covering the frequency band from 30 MHz to 10 GHz by use of the equivalent material constants method (EMCM)$^{[2]~[4]}$TEX>.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.3
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• pp.264-273
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• 2005

Broadband power line communications have been receiving tremendous interest In recent years because this technology enables utilities to deploy a communication network over existing power line infrastructures. Despite the enormous potential, there is some skepticism about the technology and its commercial viability. In this paper, we investigate the performance characteristic of PLC through field test carried out in actual households. Also it addresses major field deployment aspects, such as range, coverage, the number of node for operation and maintenance.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.4
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• pp.65-71
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• 1984

The design formular of optical focusing systems cannot be applied to ultrasonic B scanners, which use broadband pulses instead of continuous wave. In this paper, a calculation method is studied for analyzing the propagation of ultrasonic broadband pulse excited by ultrasonic array transducers. Using the results, seveial design parameters such as the number of transducer elements, delay time, and the focal point are determined to obtain high resolution in the ultrasonic dynamic focusing system. A dynamic focusing system with low-noise switching characteristics; which attains lateral resolution of 2-3mm all along the axial direction up to 18 cm with a 3.5 MHz linear array transducer, was implemented.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.341-344
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• 2000

There are many researches to increase bandwidth of the microstrip patch antenna for wireless LAN. In spite of broad bandwidth, Bow-Tie microstrip patch antenna, broadband microstrip patch antenna, has disadvantages that are low gain and big size. In this paper, stacked Bow-Tie microstrip patch antenna for wireless LAN is designed in 5.725～5.825GHz band. This antenna has characteristics that are broadband bandwidth, high gain and small size compared with microstrip patch antenna. In simulated results, the return loss is -34.2dB at 5.78GHz and bandwidth is 11.345% for VSWR is 2:1 and 7.75% for VSWR is 1.5:1. In measured results, the return loss is -38-45dB at 5.78GHz and bandwidth is 13% for VSWR is 2:1 and 5.6% for VSWR is 1.5:1.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.10
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• pp.1129-1136
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• 2008

In this paper, a dual polarized broadband antenna fed by L-shaped strip for the Korea PCS band and W-CDMA band is presented. To analyze the characteristics of the designed antenna, we used commercial simulation tool(HFSS). The designed antenna was fabricated and measured using HP8753D vector network analyzer. The measured impedance bandwidth(VSWR<1.5) is 560 MHz and the measured average gain is 6.56 dBi. The measured isolation characteristic between two ports is -14 dB(min.) $\sim$ -40 dB(max.). These results are proper for the mobile communication application and repeater antenna.